I figured it needs at least 4 energies in your hand to do decent damage, and 2 attached to the Active. And it needs Cattyton to be able to keep up that Energy stream. Therefore, I think Gatr will have to wait another set or 2 before a real combo can be established. Right now, I think it's pretty slow. However, once a Gatr is out and you met those requirements I mentioned above, it can be a real pain to get rid of it. Especially since it can use that nasty 2nd attack if the Gatr player has 3 energies or less in his hand.